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Iterator vs forEach in Java
Collections can be iterated easily using two approaches.
Using for-Each loop − Use a foreach loop and access the array using object.
Using Iterator − Use a foreach loop and access the array using object.
Differences
ConcurrentModificationException − Using for-Each loop, if an object is modified, then ConcurrentModificationException can occur. Using iterator, this problem is elliminated.
Size Check − Using for-Each, size check is not required. Using iterator if hasNext() is not used properly, NoSuchElementException can occur.
Performance − Performance is similar for both cases.
Following is an example of using above ways.
Example
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class Tester {
public static void main(String[] args) {
List<Integer> list = new ArrayList<>();
list.add(1);list.add(2);list.add(3);
list.add(4);list.add(5);list.add(6);
System.out.println("List: ");
//Way 1:
for (int i : list) {
System.out.print(i + " ");
}
Iterator<Integer> listIterator = list.iterator();
System.out.println("
List: ");
while(listIterator.hasNext()){
System.out.print(listIterator.next() + " ");
}
}
}Output
List: 1 2 3 4 5 6 List: 1 2 3 4 5 6
Updated on: 23-Jun-2020
2K+ Views
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